Method of die casting by electrical induction



Dec. 17,

METHOD OF DIE CASTING BY ELECTRICAL INDUCTION Filed March l0, 1939 BY v ATTORNEY "Patented Dec. 17, 194i) PATENT OFFICE METnon oE mE CASTING Er ELECTRICAL i INDUCTION Louis Enorm, Emn'x, N. Y., assignmto whitehall Patents Corporation', Bronx, N. Y., a corporation of New York AApplication March 10,

l6 Claims.

The present invention relates to the art of die casting and particularly to a novel method of feeding or transmittingmolten material from a pot or other container to the impression of a die in forming a predetermined casting, and more particularly the invention relates to almethodV of conveying or feeding themolten material bY electric induction. The novel fea-tures of the invention` will be best understood from the fol- 1o lowing description when taken together with the accompanying drawing, in which one embodiment of the invention is disclosed and in which the separate parts are designated by suitable reference characters, and in which: l5

view of a melting pot and discharge, illustrating one method of carrying my invention into eect,

and

Fig. 2 is a partial diagrammatic section showing another adaptation of the invention.

I n accordance with the known methods of forming die castings in the casting of various types and kinds of metals and metal alloys, the molten metals have been discharged through the conventional gooseneck or discharge nozzle into the impression of the die byvarious types and kinds' of mechanically actuated pistons or plungers, and further through the medium of compressed air. However, the objection to such known methods or processes has been in the jamming or seizing of the pistons or plungexs due to wear, the diillculty experienced by virtue of A oxidation, and various yobjecltionable features which of course have not rendered the art of a die casting inoperative, but have,brought about considerable trouble and unnecessary expense ink maintenance of the parts and in the repair thereof.

The difculty in the use of compressed air,

especially in connection with casting machines operatingl at relatively high speeds; that is to say.

in producing two hundred or more independent' castings per minute, has been in the `exhausting of the air after each injection stroke.` It will be understood that the air pressure must be relieved from the metal so as to prevent discharge of the molten material from the nozzle when the dies arenot in registering alinenient therewith,

or in other words when the dies are open to remove a pre-formed casting. On the other hand, if a quick discharge of the compressed air were permitted, this would establish a vacuum which would be sufficient to suck the metal out of ythe melting pot through the air-line pipe and clogging the line. While various types of valves Fig. 1 represents a diagrammatic sectional 1939, Serial No. 260,949 (ci. '2z-1o) havebeen tried to solve theseproblems, nevertheless the entire operation has been far from fool-proof.

To obviate the foregoing objectionable features of the presentmodes of procedure in the die castingl art, I employ an electric coil around the gooseneck or the inner end portion thereof and pass an electric current through the coil which will develop or create an velectro-motive force in the tubular gooseneck part which will 10 act upon the molten metal therein to feed the same under pressure into a die or the impression of a die. By reversing the direction of the cur-` rent, the molten metal may be moved in the opposite direction through the gooseneck. It 15 will of course be apparent 'that the entire operation of the invention will be automatic in a machine designed for the purpose intended, and

in the accompanying drawing is submitted simply a diagrammatic illustration which represents 20 the perfomance of my novel method.

In the drawing', I represents a melting pot of any particular type or kind depending entirely A upon the use to which the invention is applied.

At 2 is shown a casing or housing enveloping the 25 lower portion of the pot and preferably insulated as seen at 3. The casing forms `a combustion chamber around the pot I as at 4 having an admission end 5 in which is disposed a gas burner 8 forfheating the metal 1 in the pot I. At this 30 point it will of course be apparent thai; any type and kind of heating medium may be employed, the illustration in the accompanying drawing being simply-to represent one possible arrangement.

Supported in the upper forward side of the pot I, for example in a suitable mounting 8, is a conduit in the form of a gooseneck il having' a nozzle discharge end III and an elongated tubular end II, the bore I2 of which is exposed to the 40 metal 1 in the pot Iso that a level of the metal 1 maintained in the pot I will also be maintained inthe bore I2 of the gooseneck, substantially as is illustrated. A sealed housing or casing I3 is arranged around the tubular portion II and held 45 against displacement `therefrom by a nut I4 in threaded engagemen-twith the lower end of the tube II". Within the housing I3 and surrounding vthe tube'h is a suitably wound electric Coil I5, the--circuit wires. I6 and l1 from which ex- .50 tend outwardly through an upwardly directed tubular extension I8 on the housing I3 and are in circuit with a sui-table source oi electric sup- .ply represented by the circuit wires I9, 20 dlagrammatically illustrated at the top of Fig. 1 55 of the drawing. The circuit between the wires I9, 20 and I6 and I1 is controlled by any suitable4 being 22a, a circuit will-be formed such that the electric current will pass in one direction through the coil I5, whereas when in engagement with the contacts 23, 23a, a second circuit will be formed, .such that the current willpass through the coil I5 in the opposite direction. The coil I5 is so wound that when one of said circuits is formed, the resulting electro-motive force will feed 'the molten metal 1a, in the bore I2, into the cavity 24 of a mold 25. By closing the other circuit; the pull of the electro-motive force is reversed, thus reversing the-direction of ilowof the material 1a or that portion thereof which may remain in the bore I2, so that it will be i moved in the reversedirection, or in other words, backwardly into the pot. It will be understood that this latter operation will simply be momentary, the circuit through the coil then being 'preferably broken quickly enough so that the metal 1a in the bore will not go substantially below its original level.

It will of course be understood that in operating at high speeds, automatic means will'be provided for controlling the making and breaking of the circuits to reverse the ilow of current, and in such instances the return or inward drawing of the molten metal in the passage I2 may be checked by the reversal of the current before the metal, as at 1a, would have the opportunity to reach the level of the material 1 in the pot I. In

' other words, by proper timing of the operations of the switch 2 I, the metal in the bore I2 may be maintained at a higher level than in the pot outside the gooseneck or conduit.

As in other die casting methods, -commonly known in this art, the dies are oi' course chilledl so as to establish a substantially instantaneous solidification of the molten material, notwithstanding the fact that this material may in truth be still at a high temperature.

It 'will of course be `apparent that the various parts of the pot, gooseneclncasing, as well as the dies, Will be constructed to adapt the same for use in connection with various types and'kinds of molding materials. In' this connection it will be apparent that any suitable metals or metal alapparatus shown inthe drawing are constructed will naturally vary with the kind of molten metal whicl` is contained withinthe apparatus. It is not necessary to discuss those details for a proper understanding of the invention claimed herein.

Refractory materials may be used wherever. desired, particularly when dealing with molten metal at high temperatures. It will also be apparent that both direct and alternating currents and particularly current of high frequency may be used in carrying the. invention into effect.

In Fig. 2 of the drawing I have shown another adaptation of the invention wherein certain structural features as disclosed in'my prior Patent #2,145,553 granted January 31, 1939 are incorporated. That is to say, the tube lI Ia which takes thek'place of the tube II, includes a protruding en'd wall or stop wall II b at thelower end thereof, the tube being apertured as seen at 26 adjacent the.end Wall IIb to admit the casting material into the bore or passage I2a of the tube I Ia. With this construction, a rod 21 is arranged within Athe passage I2a and extends into the discharge nozzle Illa and seats upon the end wall I-Ib and i`s` utilized to more accurately control andlregulate the flow of material `through the tube I Ia and through the discharge of the nozzle vinto the impression 24a of a die 25a. The rod 21 will also form a tubular passage of the passage I2a thus restricting the volume of the material and facilitating the action of electric induction.

.column of metal \rather than a solid body of metal as in th structure shown in Fig. 1.

Aside from the foregoing structural differences,

the structure shown in Fig. 2 will be the same as that shown in Fig. l, the parts I3a, Ila, I5a and Ia as Well as the parts I a, 2a and 3a being of the same construction as ,the correspondingly identied parts in Fig.' l.

It will be understood that in someins'tances I may utilize what is known as polyphase winding in the coils. In fact a winding will be use d which will give the most beneflcial results with respect to the electric. induction desired to satisfy the diiferent metals oralloys that may be employed or desired in the production ol.' diierent types and kinds ofcastings. A

For the lsake of clarity and simplicity of this description, the movement of the heated or molten metal in the direction of the die may be termed upward or induced injection, whereas the other movement may be said to be' downward or induced withdrawalor suck-back. It will also appear that in a process or method of the type defined, a very simple, eilicient and substantially fool-proof method of forming diecastings is provided. It will also be understood that from time to time, small quantities of the casting material will be introduced into the pot or crucible, consistent with the formation of castings,4 as is the usual practice, thus a substantially high level of casting material is always maintained in the pot or crucible as Well as in the' bore I2, I2a.

It will be understood that the basic principles of the method herein disclosed may be utilized in conjunction with various types and kinds of apparatus or processes wherein it is desirable to move molten metal atleast in one direction through a tubular member or passage. The present illustrations are to be considered solely as diagrammatic illustrations of one adaptation of the invention.

Having fully described my invention,.what I ranged in said member, subjecting the 'molten metal within said member to an electro-motive force to move the molten metal in the direction of the discharge end of said member in pressure injecting the molten metal into the impression of a die at the discharge end of said member, and

athen subjecting the molten metal in said member to an electro-motive force operating in the opposite direction toA move the molten metal away from the discharge end of said member.

2. The herein described method of moving molten metal from a source of molten metal supply to forming means, which consists in providing a tubular passage placing the molten metal in communication with theforming means, gravity feeding molten metal into one and portion of the passage, arranging an electric coil ,around the inner end of said passage, passing a high frequency current through molten metal in said passage longitudinally of the passage and into said forming means, intermittently actuating the circuit to said coil to provide intermittent formations of castings in the forming means, and reversing the current in said coil intermediate each casting operation to reverse the flow of the molten metal in said passage.

3. The herein described method oi pressure injecting molten metal into a die cavity by electric induction in formingdie castings, which consists in providing an elongated gooseneck tube having a nozzle discharge at one end, exposing the other end portion of the tube to a source of 40 molten metal supply to normally dispose the molten metal in the bore of said second named en d portion ofthe tube, arranging a pin withthe coil to move the p 3 in the bore of the tube to form a tubular column of molten-metal therein, subjecting said tubular column ofmolten metal to an electric induction force to move said column of molten metal inthe direction of the nozzle discharge of said tube for injection into the cavity of a die supported at said nozzle discharge, and then subjecting Jthe column of molten metal in the tube to an electric induction force operating inl the opposed direction to move the molten metal in the direction of the source oi supply. 4. The method of` feeding molten metal into a mold cavity from a conduit which comprises creating an electro-motive force in the metal in said conduct, said force having a direction length- Wise of the conduit and exerting a pull towards said cavity, and then discontinuing said force and creating another electro-motive force exerting a pull in the .opposite direction lengthwise of the conduit.

5. In combination, a mold having a cavity therein, a conduit having a discharge end adjacent said cavity, means to maintain a supply of molten metal in said conduit, and means to alternately create electro-motive forces in said metal, with said forces exerting pulls lengthwise of the conduit and'one pull tending to move said metal towards the cavity andthe .other tending to move the metal away from the cavity.

6. In combination, a mold having a cavity therein, a conduit Ahaving a discharge end adjacent said cavity, means to maintain a supply of molten metalin said conduit, an electric coil surrounding said,I conduit and adapted when ener- I 

